I hear music but no video, why? FLV

[kobo_sucks]

Hi everyone,
My problem is I downloaded a Youtube video which I can view fine off-line on
Firefox courtesy of Add-On called Download Helper, but I wish to use VLC to watch the video too.

I don't see the same video working with VLC but can hear the music.
It's says its a flv but I can view the video and music fine with
Firefox through the add-on Download Helper. Do I need to convert to something?
I see a technicolor mesh instead of the video and hear the music.

I use a Firefox add called Download Helper to download Youtube video's.
I'm new to both programs (VLC and Download Helper).
I believe Firefox Download Helper saves the files as a HTML document for viewing off-line etc?

Win XP service pack 3
Firefox latest with Download Helper add-on 4.9.21

Thank you for replying

[alex4905ab]

have you used other programs to play the file to eliminate the problems with the video file?

[kobo_sucks]

have you used other programs to play the file to eliminate the problems with the video file?

Like a conversion program, no I haven't.

Downloaded a different Youtube video with Download Helper and now I
can see the video but no sound in VLC. (My Youtube audio is fine, volume not muted)

[Derek BAKER]

Try this file into other player.If the audio & video is OK then you have a problem with your VLC player.what version you have used?
If not I think its file problem.